Abstract:

A dumbbell comprises a bar that extends generally axially between opposing
end regions, a weight plate mass mounted about the bar at each end
region, means for retaining the mounted weight plate mass at the
respective end regions to define a handle region axially inward of the
end regions that can be gripped by a user during exercise movement of the
dumbbell, means for mechanically securing the weight plate mass to the
dumbbell, said bar extending sufficiently axially outward of the
mechanically secured weight plate mass to accommodate an incremental
weight plate mounted about the bar axially outward of the mechanically
secured weight plate mass, means for magnetically securing a magnetically
responsive incremental weight plate to the dumbbell via magnetic
attraction unless the mounted incremental weight plate has been rotated
about the bar to a decoupling position, and means for establishing a
decoupling position in which there is no magnetic attraction between the
mounted incremental weight plate and the dumbbell so that the incremental
weight plate can be removed from the dumbbell without overcoming the
force of magnetic attraction.

Claims:

1. A dumbbell comprising:a bar that extends generally axially between
opposing end regions,a weight plate mass mounted about the bar at each
end region,means for retaining the mounted weight plate mass at the
respective end regions to define a handle region axially inward of the
end regions that can be gripped by a user during exercise movement of the
dumbbell,means for mechanically securing the weight plate mass to the
dumbbell, said bar extending sufficiently axially outward of the
mechanically secured weight plate mass to accommodate an incremental
weight plate mounted about the bar axially outward of the mechanically
secured weight plate mass,means for magnetically securing a magnetically
responsive incremental weight plate to the dumbbell via magnetic
attraction when the mounted incremental weight plate has not been
positioned about the bar in a decoupling position, andmeans for
establishing a decoupling position for the incremental weight plate in
which there is generally no magnetic attraction between the mounted
incremental weight plate and the dumbbell so that the incremental weight
plate can be removed from the dumbbell without overcoming the force of
magnetic attraction.

2. The dumbbell of claim 1 includingan incremental weight plate has at
least one magnetic region positioned to face the weight plate mass when
the incremental weight plate is mounted on the dumbbell, andat least one
nonmagnetically-responsive region and at least one magnetically
responsive region associated the weigh plate mass, each positioned to be
generally adjacent to and generally aligned with the magnetic region of
the mounted incremental weight plate at a respective position of the
mounted incremental weight plate as the mounted incremental weight plate
is rotated about the bar.

3. The dumbbell of claim 1 including an incremental weight plate has at
least one nonmagnetically-responsive region and at least one magnetically
responsive region, each such region positioned to face axially inward
when the incremental weight plate is mounted on the dumbbell, andat least
one magnetic region associated with the weight plate mass and positioned
to be generally adjacent to and generally aligned with the
magnetically-responsive region and the nonmagnetically-responsive region
of the incremental weight plate at respective positions of the mounted
incremental weight plate as the mounted incremental weight plate is
rotated about the bar.

4. The dumbbell of claim 1 includingan incremental weight plate has at
least one magnetic region positioned to face the weight plate mass when
the incremental weight plate is mounted on the dumbbell, andat least a
pair of magnetic regions associated with the weight plate mass, each
positioned to be generally adjacent to and generally aligned with the
magnetic region of the mounted incremental weight plate at a respective
rotational position of the mounted incremental weight plate about the
bar,one of the magnetic regions associated with the weight plate mass
having a magnetic polarity that attracts at least one magnetic region of
the incremental weight plate to magnetically secure the incremental
weight plate to the dumbbell, andone of the magnetic regions associated
with the weight plate mass having a magnetic polarity that repels at
least one magnetic region of the incremental weight plate to magnetically
repel the incremental weight plate from the weight plate mass.

5. The dumbbell of claim 1 includingan incremental weight plate having at
least a pair of magnetic region positioned to face the weight plate mass
when the incremental weight plate is mounted on the dumbbell, andat least
one magnetic region associated with the weight plate mass and positioned
to be generally adjacent to and generally aligned with the magnetic
regions of the mounted incremental weight plate at a respective
rotational position of the mounted incremental weight plate about the
bar,one of the magnetic regions associated with the incremental weight
plate having a magnetic polarity that is attracted to a magnetic region
associated with the weight plate mass to magnetically secure the
incremental weight plate to the dumbbell, andone of the magnetic regions
associated with the incremental weight plate having a magnetic polarity
that is repelled by a magnetic region of the weight plate mass to
magnetically repel the incremental weight plate from the weight plate
mass.

Description:

CLAIM OF PRIORITY

[0001]This is a continuation-in-part of U.S. application Ser. No.
11/425,962 filed Jun. 22, 2006 and a continuation-in-part of U.S.
application Ser. No. 11/425,968 filed Jun. 22, 2006, the priorities of
which are claimed and the contents of which are hereby incorporated by
reference.

FIELD OF THE INVENTION

[0002]This invention pertains to exercise apparatus of the type employing
movable weight plates. Examples of such devices are barbells, dumbbells
and cabled devices such as the popular Universal machine that utilize
adjustable stacks of weight plates to resist the user's exercise
movement. The foregoing equipment shall hereinafter be collectively
referred to as "weight plate devices", and the term "weight plate device"
will be utilized to refer to one or more of them.

[0003]There are two fundamental types of dumbbells and barbells: the
"fixed weight" type, wherein the weight plates are permanently secured on
the ends of a bar, and the "adjustable" type, wherein weight plates are
secured on the bar by removable collars that permit the user to add or
remove individual weight plates to the bar. The fixed weight type is
typically part of a set wherein a plurality of dumbbells (or barbells)
provide a range of weights typically separated by 5 lb. increments.

[0004]Typically, it is desirable to have an easily and quickly mountable
and detachable weight plate that can be used to selectively add or
subtract incremental weight to a pre-existing weight plate combination or
other pre-existing weight-training mass. For simplicity, this easily
mountable and detachable weight plate will be referred to as an
"incremental" weight plate because (as will become clear) it is used to
incrementally vary the weight to be lifted. In some cases, the
incremental weight is quite small; e.g., 0.25 to 2.5 lbs. In other cases,
it can be greater or smaller. Generally, incremental weights are used to
rehabilitate injured muscles and ligaments, wherein small
increases/decreases in resistance are needed in the course of
rehabilitation exercises. In other cases, small incremental weights are
useful where the user is exercising smaller muscle groups, or is older or
physically weak, or has reached a "plateau" that is preventing a major
increase to the next full increment of lifted poundage.

[0005]The use of magnetically mountable incremental weights is known as
one means to quickly and conveniently add and subtract such weight. For
example, U.S. Pat. No. 5,735,777 describes the use and application of
magnetic "adaptive weights" that are removably attached to dumbbells and
barbells. The content of that patent is hereby incorporated by reference.

[0006]The advantages of magnetically coupled incremental weights have been
offset by a number of deficiencies. First, they have not been usable with
non-metallic weight plates although many dumbbells and barbells utilize
plastic weight plates or plates made of other non-magnetic material. In
addition to being less expensive to manufacture, plastic and rubber
weight plates are less prone to cause chipping, marring and other surface
damage to surrounding gym equipment such as racks and neighboring
devices, and are less prone to damage inadvertently contacted woodwork
and walls. Accordingly, the inability to use magnetically coupled
incremental weight plates with increasingly popular non-magnetic dumbbell
and barbell weight plates is a severe limitation.

[0007]Secondly, there has been a need for strong magnetic attraction
between the incremental weight plate and the dumbbell/barbell weight
plate to which it is attached. In addition to safety concerns that arise
whenever a weight plate can fall from an exercise device, it is
undesirable for the incremental weight to shift position during an
exercise movement because the resulting imbalance can detract from the
safety and efficacy of the exercise movement. The strong magnetic
attraction thus required not only makes it difficult to remove the
incremental weight plate from the exercise device, but can also scratch
or mar the weight plate surface to which the incremental weight attaches.
Moreover, magnetic incremental weights are coupled to coated weight
plates on some weight plate devices, and the decoupling effort can
scratch or mar the coating, leading to the rusting of the underlying
surface.

SUMMARY OF THE INVENTION

[0008]A dumbbell is disclosed herein comprising a bar that extends
generally axially between opposing end regions, a weight plate mass
mounted about the bar at each end region, means for retaining the mounted
weight plate mass at the respective end regions to define a handle region
axially inward of the end regions that can be gripped by a user during
exercise movement of the dumbbell, means for mechanically securing the
weight plate mass to the dumbbell, said bar extending sufficiently
axially outward of the mechanically secured weight plate mass to
accommodate an incremental weight plate mounted about the bar axially
outward of the mechanically secured weight plate mass, means for
magnetically securing a magnetically responsive incremental weight plate
to the dumbbell via magnetic attraction when the mounted incremental
weight plate has not been positioned about the bar in a decoupling
position, and means for establishing a decoupling position in which there
is no magnetic attraction between the mounted incremental weight plate
and the dumbbell so that the incremental weight plate can be removed from
the dumbbell without overcoming the force of magnetic attraction.

[0009]In accordance with one embodiment of the invention, the cessation of
magnetic attraction is accomplished by a decoupling position wherein one
or more magnetic regions of the incremental weight plate are
substantially aligned with respective non-magnetically responsive regions
of the dumbbell (and/or wherein one or more non-magnetically responsive
regions of the former are substantially aligned with respective magnetic
regions of the latter) to permit the incremental weight plate to be
easily removed from the dumbbell.

[0010]In accordance with another embodiment of the invention, the
cessation of magnetic attraction is accomplished by aligning magnetic
regions of the incremental weight plate with magnetic regions of opposite
polarity associated with the dumbbell to cause a magnetic repulsion of
the incremental weight plate from the dumbbell, aiding in its removal.

[0011]These and further details of the invention will be apparent to those
of ordinary skill in the art from reading a description of the preferred
embodiment of the invention described below, and of which the drawing
forms a part.

DESCRIPTION OF THE DRAWING DRAWINGS

[0012]FIG. 1 is a front elevation view showing one end of a dumbbell
constructed in accordance with the invention herein;

[0013]FIG. 2 is a left side elevation view of the dumbbell of FIG. 1;

[0014]FIG. 3 is a front elevation view of the dumbbell illustrated in FIG.
1 with an added incremental weight plate mounted onto its bar in
accordance with the invention;

[0015]FIG. 4 is a front elevation view of the dumbbell of FIG. 1 with the
incremental weight plate fully mounted;

[0016]FIG. 5 is a right side elevation view of the incremental weight
plate shown in FIG. 4;

[0017]FIG. 6 is a front elevation view of the dumbbell of FIG. 1 with the
incremental weight plate fully mounted;

[0018]FIG. 7 is a left side elevation view of the dumbbell of FIG. 6;

[0019]FIG. 8 is a front elevation view of a second embodiment of a
dumbbell constructed in accordance with the invention;

[0020]FIG. 9 is a front perspective elevation view of the dumbbell of FIG.
8, showing the incremental weight plate positioned for mounting onto the
dumbbell in accordance with the invention;

[0021]FIG. 10 is a right side elevation view of the plate and sleeve of
FIG. 8;

[0022]FIG. 11 is a left side elevation view of the right incremental
weight plate illustrated in FIG. 9;

[0023]FIG. 12 is a front elevation view of a dumbbell constructed in
accordance with a third embodiment of the invention;

[0024]FIG. 13 is a left side elevation view of the dumbbell of FIG. 12;

[0025]FIG. 14 is a rear elevation view in schematic of a cabled exercise
device constructed in accordance with a fourth embodiment of the
invention and

[0026]FIG. 15 is a perspective view of another embodiment of a dumbbell
constructed in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0027]FIG. 1 is a front elevation view showing one end of a "fixed weight"
type dumbbell 10 constructed in accordance with the invention. Although
the invention is discussed in the context of a dumbbell, it should be
recognized that barbells are within the scope of the invention and the
term "dumbbell" will be used to denote both devices.

[0028]The dumbbell 10 has a weight plate mass comprising, in the
illustrated embodiment, two generally annular weight plates 12
respectively mounted in the conventional manner at opposite end regions
of a longitudinally-extending bar 14 and mechanically secured thereto in
the conventional manner as, for example, as by press fitting the plates
onto the bar and/or welding or bolting them in place. In FIG. 1, only the
left weight plates 12 are shown, the right weight plate having been
omitted for the purpose of illustration. In practice, a plurality of
weight plates may be mounted at each end region to achieve the desired
weight, or a single weight plate may be utilized at each end region. The
end portion of the bar 14 extends through and beyond the outermost weight
plate 12. The weight plates abut respective collars 11 which are located
at longitudinally opposed positions on bar 14 to define a handle region
13 therebetween that is gripped by the user. The weight plates 12 may be
formed (at least in part) from a magnetically responsive material such as
iron or steel. The axially outermost of the plates 12 at each end region
may be weight plates intended to significantly contribute to the weight
of the dumbbell (as do conventional weight plates) or they may be of
comparatively insubstantial weight (see, for example, plate 42 in FIG.
15) intended only to provide the magnetic coupling and/or decoupling
feature as hereinafter described. As described herein, the axially
outermost weight plates 12 will be illustrated and described as a weight
plate, but those of ordinary skill in the art will recognize that it need
not be a significant, or even noticeable, contributor to the weight of
the dumbbell.

[0029]FIG. 2 is a left side elevation view of the dumbbell of FIG. 1. A
pair of magnets 16, 18 are associated with the weight plate mass; magnets
16, 18 are embedded in the outermost surface of the plate 12 at both ends
of the dumbbell. The magnets are preferably of the rare earth type, such
as neodymium magnets. These are very strong magnets that can be relied
upon to securely bind a magnetically-responsive incremental weight plate
to the dumbbell. While two magnets 16, 18 are shown in diametrically
opposite positions, any other number of magnets could be used, and other
positions could be utilized without departing from the scope of the
invention.

[0030]In the configuration illustrated in FIG. 2, the magnets 16, 18 have
poles of like polarity facing axially outward; i.e., their North poles.
As will become clear, however, both magnets can instead have their South
poles facing axially outward, or each can have a different pole facing
axially outward without departing from the scope of the invention. Also,
as will become clear, the number of magnets is not limited to "two", but
can be any number, and their respective outwardly-facing poles can be
North poles, South poles, or a mix thereof that accomplishes the purposes
hereinafter described. Lastly, one of ordinary skill in the art will
recognize that the axially outermost plate 12 can be of any thickness or
cross-dimension, and can be fabricated to provide a standardized amount
of weight (or negligible weight) to each dumbbell on which it is placed,
thereby enabling that same magnet-bearing plate to be used in the
fabrication of dumbbells of different weights.

[0031]The dumbbell illustrated in FIGS. 1 and 2 has a "base weight" to
which an incremental weight plate of desired poundage is to be added.
FIG. 3 is a front elevation view of the dumbbell of FIG. 1, but showing
an incremental weight plate 20 of incremental poundage mounted onto the
outwardly extending portion of the bar 14. The incremental weight plate
20 preferably includes an integrally formed knurled portion 22 that can
be of relatively larger diameter, if desired, which provides a graspable
periphery preferably sized to be encompassed by the human hand so that
the incremental weight plate 20 can be rotated with one hand in the
manner of a jar-top.

[0032]FIG. 4 is a front elevation view of the dumbbell of FIG. 1 with the
incremental weight plate fully mounted. FIG. 5 is a right side elevation
view of an incremental weight plate constructed in accordance with the
invention. This is the axially inwardly-facing surface of the incremental
weight plate 20 of the dumbbell depicted in FIGS. 1-4; i.e., the surface
that faces and engages the weight plate 12. As illustrated in FIGS. 3-5,
the incremental weight plate 20 is preferably generally annular, so as to
fit concentrically about the bar 14. The incremental weight is thereby
balanced with respect to the bar, as is preferable for most lifting
movements. Naturally, other shaped plates or non-concentric mountings can
be provided if an unbalanced arrangement is desired. As further
illustrated in FIG. 7, indicia can be stamped, molded or otherwise placed
upon the incremental weight plate to display its added incrementally
poundage; in this case, "21/2" indicates that the incremental weight
plate 20 ways 21/2 pounds.

[0033]As shown in FIGS. 3 and 5, the incremental weight plate 20 includes
a pair of magnets 24, 26 that are embedded in the incremental weight
plate and positioned to generally overlie the magnets 16, 18 when the
incremental weight plate is mounted onto the bar 14 and rotated into a
"decoupling" position as described below. The term "generally overlie"
means that the magnets are sufficiently adjacent to create the desired
magnetic interaction between them. While the magnets 24, 26 have axially
inward-facing North poles in FIG. 5, it should be understood that this is
the case because the magnets 16, 18 of the dumbbell mass (FIG. 2) have
axially outward-facing North poles. Generally, this variant of the
invention contemplates only that the dumbbell magnets magnetically repel
the incremental weight plate magnets when the latter are brought into
substantially overlying relationship with the former so that the
incremental weight plate will be magnetically repelled from the dumbbell
mass.

[0034]When the incremental weight plate is mounted on to the bar 14, and
positioned so that its magnets do not interact with respective like poles
of the dumbbell mass, the incremental weight plate 20 becomes
magnetically secured to the magnetically responsive plate 12 (and thereby
to the dumbbell) without the need for a collar. When the user wishes to
decouple the incremental weight plate 20 from the dumbbell, the user
merely grips and rotates the outer knurled periphery of the incremental
weight plate with one hand, in the manner by which ajar top is gripped
and rotated. The incremental weight plate 20 is then rotated about the
bar 14 until the magnets 24, 26 interact with the magnets 16, 18 and are
magnetically repelled so that the incremental weight plate seemingly
"pops off" the dumbbell. The user need only have applied a relatively
easy twisting motion to the incremental weight placed 20 rather then
pulling the plates apart. For convenience, the incremental weight plate
can be marked with a symbol that, when lined up or otherwise correlated
with a symbol on the dumbbell as the incremental weight plate is rotated,
indicates the decoupling position to the user. In its simplest form, a
line 23a (FIG. 6) or dot on the perimeter of the incremental weight plate
can be rotated into alignment with a line 23b or dot on the periphery of
the plate 12.

[0035]The magnets 24, 26 that have been successfully used are 0.5 inches
in diameter and 0.5 inches in length, with a tolerance of 0.005 inches.
They are slip-fit into respective bore holes in the incremental weight
plate, and the top of the bore walls are center punched radially inward
around their peripheries to entrap the magnets within the bores.

[0036]To prevent the rotated magnets from marring the surfaces of the
weight plates 12 and the incremental weight plates 20, the magnets are
preferably recessed from the surfaces of the respective plates by 10
thousandths of an inch or so.

[0037]Those skilled in the art will recognize that a greater number of
magnets could be used, and that they can be positioned differently than
those shown in the Figures. Regardless of the number of magnets or their
respective positions, the magnets are utilized to attract or repel the
incremental weight plate.

[0038]The use of mutually attracting magnets can provide for a more secure
coupling of the incremental weight plate to the dumbbell than the
aforedescribed coupling to the plate 12's magnetically responsive
material, yielding a greater safety factor and/or permitting weaker and
perhaps less expensive magnets to be used. In another magnetic
arrangement, magnets of the incremental weight plate and dumbbell are
accordingly oriented and positioned to magnetically attract each other
when the incremental weight plate is mounted onto the dumbbell in a first
(or "securing") position, and magnetically repel each other when the
incremental weight plate is rotated to a second (or "decoupling")
position. In the first position, one or more axially-inward facing poles
of the magnets in the incremental weight plate magnetically couple to
axially-outward facing poles of opposite polarity of magnets associated
with the weight plate 12 that they generally overlie; for example,
axially inward-facing North poles in the incremental weight plate face
axially-outward South poles of the weight plate 12. In the decoupling
position, the axially-inward facing poles of the magnets in the
incremental weight plate face magnets associated with the weight plate 12
that have like magnetic polarities; for example, axially inward-facing
North poles in the incremental weight plate face axially-outward North
poles of the weight plate 12. As few as three magnets can be used, with
either the weight plate 12 or the incremental weight plate having one
magnet having either a North pole or South pole, and the other of the two
plates having two magnets: one with a South pole and one with a North
pole. Thus one paired coupling will attract the incremental weight plate
to the dumbbell, and the other paired coupling will magnetically repel
the incremental weight plate from the dumbbell. More magnets can be used
with their respective poles positioned and oriented to accomplish the
foregoing functions.

[0039]Another variant of a dumbbell constructed in accordance with the
invention is shown in FIGS. 8-11. FIG. 8 is a front elevation view of a
dumbbell 30 of the "adjustable" type, wherein weight plates have
conventionally been mechanically secured on the bar by removable collars
that permit the user to add or remove individual weight plates to the
dumbbell. FIG. 9 is a front perspective elevation view of the dumbbell of
FIG. 8, and FIG. 10 is a side elevation view of the dumbbell of FIG. 8,
showing an incremental weight plate 34 mounted onto the dumbbell in
accordance with the invention.

[0040]In this embodiment, the bar 35 is of the known externally-threaded
variety. Conventionally, weight plates are mounted on the bar and urged
toward the dumbbell's handle until stopped by the collar 36 or a
previously mounted weight plate. An internally threaded nut or other such
fastening device is then rotated onto the bar until securing contact is
made with the outermost weight plate.

[0041]As illustrated in FIGS. 8-9, the outer weight plates 32 and
incremental weight plates 34 are mounted at opposite end regions of an
externally threaded bar 35 that extends through the dumbbell handle 37.
As will become clear, the outer weight plates 32 of the weight plate mass
need not be magnetically responsive but can, instead, be made of
polyurethane or other commonly utilized plastic material such as that
found in less expensive dumbbell sets.

[0042]In accordance with the invention, and as best shown in FIGS. 9 and
10, a sleeve 40 is mounted to the bar 35. The sleeve preferably has a
"T"-shaped cross-section, comprising an internally-threaded generally
cylindrical portion 41 that is tightened onto the externally threaded bar
35, so that a leading plate portion 42 of relatively greater diameter
butts up against the outer weight plate 32 to mechanically secure the
weight plate 32 to the bar. The cylindrical portion 41 provides a
relatively smooth mounting surface for the incremental weight plate,
preventing the mounting operation from being adversely affected by the
discontinuous surface created by the external threads of the shaft 35.

[0043]Those of ordinary skill in the art will recognize that the plate
portion 42 need not be integral with the cylindrical portion 41; where
the two are separate components, a plate 42 can simply be mounted about
the bar 35, and an internally threaded sleeve 41 can be tightened onto
the externally threaded bar 35 until the plate 42 is secured against the
outermost weight plate 32. It will hereinafter be understood that the
term `plate portion 42" will be used to refer to both the plate portion
of the sleeve 40 and the alternative separate plate, while the term
"cylindrical portion" will likewise be used to refer to both the
cylindrical portion 41 of the sleeve 40 and the separate sleeve 41 just
described.

[0044]Depending on the specific embodiment, the plate portion permits one
or more magnetic regions, one or more magnetically-responsive regions,
and/or one or more nonmagnetically-responsive regions to be associated
with the weight plate mass even where the weighplate mass is formed from
a non-magnetic material or has a nonmagnetic coating that renders the
mass weakly magnetically-responsive or magnetically non-responsive. In
one variant of the plate portion 42, the plate portion 42 is formed at
least partially from magnetically responsive material so that the
incremental weight plate becomes magnetically secured to the plate
portion 42 when mounted on the dumbbell even if the weight plate 32 is
non-magnetically responsive. (It will also be recognized by those of
ordinary skill in the art that a relatively thin plate similar to plate
portion 42 can be utilized on a "fixed weight" dumbbell such as that
illustrated in FIGS. 1-6 if one wishes to use non-magnetic material or
non-magnetic coatings to form at the axially outermost weight plate 12
thereof.) The incremental weight plate is are accordingly provided with
one or more magnetic regions, such as magnets 38 (FIG. 11) that secure
the incremental weight plate to the plate portion and, thereby, to the
dumbbell. FIG. 11 is a left side elevation view of the right incremental
weight plate 34 of FIG. 8, showing two magnets 38. As before, and as
preferred, the magnets have like poles facing the dumbbell; i.e., each
has its North pole facing the dumbbell, or each has its South pole facing
the dumbbell.

[0045]A second variant of the plate portion 42 is formed from a
non-magnetic material, but includes separate regions of magnetically
responsive material embedded therein that are positioned to interact
magnetically with the incremental weight plate 34 (FIG. 11) when the
incremental weight plate is mounted onto the bar. In FIG. 15, for
example, the region 39 is positioned to magnetically interact with the
incremental weight plate 34. There may be one or more such magnetically
responsive regions 39; preferably, there is a second such region
diametrically opposite the magnetic region 39 visible in FIG. 15 but
hidden from view in that Figure by the sleeve 40. The region(s) 39 is
positioned to magnetically interact with the regions 38 (FIG. 11) when a
region 38 is adjacent to a region 39. At least one of that adjacent pair
must be a magnet, with the other of the adjacent pair being either a
magnet of opposite polarity or simply magnetically-responsive material.
Thus, for example, region 39 may be a region of magnetically-responsive
material, while region 38 (FIG. 11) is a magnet. When the incremental
weight plate 34 is mounted on the bar with region 39 adjacent region 38,
the incremental weight plate is magnetically secured to the dumbbell.
When the incremental weight plate is rotated about the shaft 35 to move
region 38 away from region 39 until the regions are magnetically
uncoupled, the incremental weight plates can be manually removed from the
dumbbell without the need to physically overcome the magnetic attraction
that secured the incremental weight plate to the dumbbell. Naturally, the
magnet(s) can be located in the plate portion 42, with magnetically
responsive and non-magnetically responsive regions being positioned on
the incremental weight plate to achieve the same result. Those skilled in
the art will recognize that the magnetically responsive and
non-magnetically responsive regions can be of any shape, dimension and
location that achieves the described effect, and that any number of such
regions may be utilized on the plate and on the incremental weight plate
that achieves that effect.

[0046]In a third variant of the plate portion 42, both the plate portion
and the incremental weight plate are provided with magnets whose poles
selectively cause magnetic attraction and magnetic repulsion of the
incremental weight plate with respect to the dumbbell, depending upon the
rotational position of the incremental weight plate about the bar.
Accordingly, the plate portion 42 and the incremental weight plate 34 of
this variant each include at least one magnet oriented and positioned to
experience magnetic repulsion when the incremental weight plate is
rotated about the bar into a decoupling position that rotates its magnet
into a position substantially adjacent the plate portion's magnet. By way
of example, if the region 39 (FIG. 15) represents a magnet having an
axially outward-facing North pole and the incremental weight plate 34 has
a magnet 38 (FIG. 11) with an axially inward-facing North pole, the
region 39 magnetically secures the incremental weight plate to the
dumbbell, when the incremental weight plate 34 is magnetically attracted
to magnetically responsive material associated with the plate portion 42
(or to a magnet associated with plate portion 42 that has an
axially-outward facing South pole). The incremental weight plate can then
be rotated about the bar 35 into a decoupling position, wherein the
magnetic North poles of regions 39 and 38 interact, repelling the
incremental weight plate 34 from the plate portion 42.

[0047]Thus, the plate portion 42 and/or incremental weight plate 34 may
also be provided with magnets presenting North and South poles to the
other so that a rotation of the incremental weight plate creates one or
more coupling and decoupling positions. For example, as illustrated in
FIG. 15, the plate portion 42 can include two magnets 39 that
respectively present a North and a South pole to the magnets of the
incremental weight plate 34 for the coupling/decoupling effect previously
described. A given magnetic pole associated with the plate portion 42
will attract one of the magnets 39, and repel the other, thereby
providing both magnetic attraction and magnetic repulsion.

[0048]Again, those of ordinary skill in the art will recognize that any
number of magnets, locations and orientations can be used to achieve the
foregoing effect. For example, two magnets may be placed 180°
apart (or less) or four magnets may be placed 90° apart (or less)
to reduce the degree of rotation needed to reach a decoupling position.

[0049]Regardless of the particular magnetic arrangement chosen, the plate
portion 42 provides a magnetically responsive seat for the incremental
weight plate 34 regardless of whether the axially outer weight plate 32
is made of magnetically-responsive material or not. Further, the plate
portion 42 provides a wear surface that prevents the axially outer weight
plate 32 from being marred or damaged by the incremental plate 34,
particularly when the outer plate 32 is plated or coated with an
aesthetically pleasing layer of material.

[0050]The sleeve 40 may, if desired, be tightened onto the bar 35 by
mounting the sleeve and magnetically coupled incremental weight plate 34
together as a unit, and utilizing the incremental plate 34 as a handle in
a jar-lid tightening manner. To enable the sleeve 40 to be more firmly
tightened onto the bar, however, a series of longitudinally-extending
grooves 44 are preferably formed in the cylindrical portion 41 of the
sleeve for gripping by complimentary surfaces of a tightening tool. This
is best shown in FIG. 10, which is a right side elevation view of the
sleeve 40.

[0051]FIG. 12 illustrates another embodiment of the invention. FIG. 12 is
a front elevation view of a dumbbell of the "fixed weight" type, wherein
weight plates 52 are permanently secured on the ends of a bar that
extends through the dumbbell handle 58. FIG. 13 is a side elevation view
of the dumbbell of FIG. 12. Again, the weight plates 52 may be
magnetically responsive or not. A plate 60 having one or more
magnetically-responsive regions is secured to the dumbbell at each end
region of the dumbbell between the axially outermost weight plate 52 and
a generally annular, longitudinally-extending cylindrical sleeve 54. The
plate 60 has a relatively larger diameter than the sleeve 54, and the two
are preferably formed as an inter-pole piece. The sleeve is secured to
the dumbbell via a respective hex bolt 59 that is inserted into the end
57 of the sleeve 54, extends through the sleeve and threads into an
internally threaded end region of the bar, thereby securing the sleeve
54, plate 60 and weight plate 52 against respective collars 56 located at
each end of the handle 58. Incremental weight plates can then be added
and removed as described above, preferably but not necessarily utilizing
magnets in the plate 60 to repel the incremental weight plate when the
incremental weight plate is rotated to bring its magnet(s) into general
alignment with the like-pole of opposing respective magnet(s) in the
plate 60.

[0052]The invention herein is not limited to dumbbells or barbells. It
can, for example be applied to cable-type exercise equipment. FIG. 14 is
a rear elevation view in schematic of a cabled exercise device
constructed in accordance with a fourth embodiment of the invention. An
adjustable stack of weight plates 70 is lifted by a user who is pulling
them upward by a cable 72 via a pulley 71 or other means known in the
art. The stack of weight plates is guided by guide rods 73, which guide
the stack's movement vertically, and keep the plates evenly stacked as
they move. "Sleeves" with magnetically-responsive base portions may be
affixed, as at 74, to the topmost weight plate to accommodate incremental
weight plates, thereby offering a total poundage that falls between the
increments of weight offered by the stack. The base portions of the
"sleeves" may include magnets, as described above, to repel the
incremental weight plate when the incremental weight plate is
appropriately rotated, or the sleeve. The "sleeves" need not be annular
in this application, and the term "sleeve" has been used only for
consistency of terminology with respect to embodiments described above.

[0053]Alternatively, the "sleeves" of this embodiment can be positioned as
at 76, with the incremental weight plates being held magnetically above
the stack until needed, and then being selectively decoupled from the
"respective" sleeve and guided vertically about the respective guide rod
73 from the "sleeve" to the weight plate stack. Once again, the
decoupling action can be purely manual, or the "sleeves" can include
magnets in their base portions to repel the incremental weight plate when
the incremental weight plate is suitable rotated, as described earlier.

[0054]Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing from
the spirit and scope of the invention as will be defined by appended
claims.